Advancing microgrid technology with engineering, innovation, and good will

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From automated factory design in corporate America to pioneering microgrids in energy impoverished communities around the world, Minnesota’s University of St. Thomas Professor Dr. Greg Mowry is now working on a state-of-the-art research microgrid design that can facilitate widespread deployment of the technology. Professor Mowry’s extensive fieldwork led him to conduct research into constructing a more resilient, reliable and cost-effective microgrid at the University of St. Thomas Renewable Energy Facility. Funding has been made possible by a $2.1 million grant from the Xcel Energy Renewable Development Fund (RDF).

Professor Mowry’s field work on microgrids began in 2004 when he built small power systems in Moldova, a country whose power grid collapsed along with the Soviet Union. “How do you regenerate a power grid when you can’t afford it?” he asked. The answer at the time was to construct a series of what he and his team members simply called small power systems because the term “microgrid” had yet to be popularized. He joked that they should have recognized the radical nature of what they were doing and coined the term “microgrid” themselves.

Mowry went on to design and build these small electricity networks in African countries and other rural locations. This work revealed two major technological challenges, that if overcome, would greatly increase the flexibility and resiliency of microgrids: Better inverter design and distributed intelligence to control and operate the systems.

Interestingly and coincidentally, upon receiving the RDF grant and searching for partners, Professor Mowry found a firm — Rhombus Energy Solutions, Inc. — that was independently working toward similar goals of distributed power conversion and control. They were working on the same things but didn’t know it and their respective missions dovetailed very well explained Mowry. “Either misery loves company or we independently saw a better way to do something.”

After an extensive review of potential suppliers, Professor Mowry selected Rhombus Energy as a partner, supplying both intelligent inverters as well as a system wide energy management software platform, named VectorStat®. Rhombus intends to work with the university on directed research focused on optimizing how microgrids are controlled. Rhombus Energy’s technology is helping to develop robust, reliable, cost effective, resilient and adaptable control systems, explained Mowry.

The university’s microgrid is designed to have equal power output from wind, solar PV, biodiesel generator sets and battery storage. Each of these will nominally output 50 kilowatts (kW) and the system has provisions for two additional 50 kW sources, like a fuel cell for example, that can be connected. All energy resources are designed to be about the same size so no single source is dominant. Control systems will need to manage similarly sized power supplies. If they can do this, then they should be able to handle microgrids that operate in a distributed, peer-to-peer control and are not dominated by a single source.

Early automated factory design was built around central control so any blip would knock the whole factory offline. “It’s not that you can’t do centralized control, it’s just that if there is a problem the whole thing shuts down,” Mowry said. Load hierarchy is a good way to think about it. For example, a hospital needs to power its emergency room and refrigeration more than offices or cafeteria during a power failure. Distributed intelligence helps do this in a natural way.

Another exciting aspect of the university’s research microgrid is the provision for additional resources, which allows third parties to test and experiment with their microgrid technology. This is easier said than done because there are few operational microgrids in the U.S. and the ones that do exist are not necessarily designed for this type of experimentation. If a company has a microgrid product they want to test, they either need to find a suitable existing microgrid or build their own, which can be prohibitively expensive. The university encourages such third-party involvement by handling intellectual property in a flexible manner. Their goal is to advance affordable, reliable renewable energy deployment to help energy impoverished communities around the world.

Two-thirds of the planet lacks access to electricity. “Outside the United States the microgrid is the future,” says Mowry. The whole point behind Professor Mowry’s research is to find better and simpler ways to make microgrids more resilient so they last. “The humanitarian impact alone could be really substantive, it’s worth the effort,” he said.